more entrypoint macros

src/draw.rs

@@ -7,13 +7,22 @@ use crate::*;
 /// struct TestOut { w: u16, h: u16 };
 /// impl Wide<u16> for TestOut {}
 /// impl Tall<u16> for TestOut {}
-/// impl Xy<u16> for TestOut { fn x (&self) -> u16 { 0 } fn y (&self) -> u16 { 0 } }
+/// impl Xy<u16> for TestOut {
+///     fn x (&self) -> u16 { 0 }
+///     fn y (&self) -> u16 { 0 }
+/// }
 /// impl Screen for TestOut {
 ///     type Unit = u16;
-///     fn show <D: Draw<Self>> (&mut self, _: D) -> Drawn<u16> {
-///         println!("placed");
-///         Ok(None)
-///     }
+///     fn show (&mut self, _: impl Draw<Self>) -> Perhaps<XYWH<u16>>
+///         { println!("placed"); Ok(None) }
+///     fn area (&self) -> XYWH<Self::Unit>
+///         { Default::default() }
+///     fn clip <T> (
+///         &mut self,
+///         area: impl Into<Option<XYWH<u16>>>,
+///         draw: impl FnOnce(&mut Self)->T
+///     ) -> T
+///         { draw(self) }
 /// }
 ///
 /// impl_draw!(|self: String, to: TestOut|{